KR20140120940A - Aqueous solution which efficiently absorbs and recovers carbon dioxide in exhaust gas, and method for recovering carbon dioxide using same - Google Patents

Abstract

What is disclosed is an aqueous solution for absorbing and recovering carbon dioxide from a gas containing carbon dioxide and is an aqueous solution containing an aminoalcohol compound represented by the general formula (1) and an amine compound represented by the general formula (2) (Wherein, X represents -NR 1 R 2, Y represents -NR 3 R 4, R 1, R 2, R 3 and R 4 are the same or different and each represents a carbon number of 1 to 5 And m represents an integer of 3 to 7).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an aqueous solution for efficiently absorbing and recovering carbon dioxide in exhaust gas, and a method for recovering carbon dioxide using the same. [0002] Japanese Patent Application Laid-

The present invention relates to an aqueous solution for absorbing and recovering carbon dioxide contained in a gas and a method for efficiently absorbing and recovering carbon dioxide in a gas using the aqueous solution.

In recent years, climate change and natural disasters, which are thought to be caused by global warming, have a huge impact on agricultural production, domestic environment, and energy consumption. This global warming is thought to be due to the increase in the greenhouse gas represented by carbon dioxide, which increases with the active industrial activities of mankind, and measures for reducing the atmospheric concentration are urgently needed.

The main sources of carbon dioxide are coal, heavy oil, natural gas, coal-fired power plant, kiln in a boiler or cement factory in a manufacturing plant, furnace in a steel making plant to reduce iron oxide, automobile fueled by gasoline, heavy oil, , Ships, aircraft, and other transport equipment. Among these, fixed facilities are excluded from transportation equipment, and it is expected to be an easy facility to take countermeasures for reducing the atmospheric release of carbon dioxide.

Although a wide variety of methods are now being studied for a method for recovering carbon dioxide in the exhaust gas from the sources exemplified above, a few methods have been known so far.

For example, a method of absorbing carbon dioxide by contacting a gas containing carbon dioxide with an aqueous solution of an alkanolamine in an absorption tower is well known. Examples of the alkanolamine include monoethanolamine (hereinafter sometimes referred to as MEA), diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA) Amine (DGA) and the like are known, but MEA is usually used.

However, when the aqueous solution of these alkanolamines is used as the absorption liquid of carbon dioxide, since the primary corrosive property of the apparatus is high in primary amines such as MEA, it is necessary to use expensive corrosion resistant steel or to reduce the amine concentration in the absorption liquid . In addition, the desorption of the absorbed carbon dioxide is generally carried out in a regeneration tower at about 120 ° C to desorb and recover the carbon dioxide. In the alkanolamine described above, the amount of carbon dioxide absorbed in the absorption tower and the amount of carbon dioxide The amount of desorbed carbon dioxide is not sufficient, and consequently, a large energy is required for recovery per unit of carbon dioxide unit weight.

In a time when generation of carbon dioxide is required to be cut down, energy saving and resource saving are required, a large amount of energy consumption in the absorption and recovery of carbon dioxide is a major factor preventing commercialization of the technology, Technology is required.

As a conventional technique for separating and recovering carbon dioxide at a lower energy, for example, Patent Document 1 discloses a method of separating and recovering carbon dioxide from a solution of so-called hindered amine having steric hindrance of an alkyl group or the like around an amino group and a combustion exhaust gas under atmospheric pressure A method of removing carbon dioxide in a fuel exhaust gas by a method in which carbon dioxide is absorbed by contact with the exhaust gas.

Herein, examples of hindered amines include 2-methylaminoethanol (hereinafter sometimes referred to as MAE) and 2-ethylamino ethanol (hereinafter sometimes referred to as EAE), wherein 30% by weight of MAE and EAE, Is used in the examples. As other hindered amines, there are no examples, but amines such as 2- (isopropylamino) ethanol (hereinafter sometimes referred to as IPAE) are described.

Patent Documents 2 to 6 disclose a method for producing an aqueous solution containing N, N, N ', N'-tetramethyl-1,3-butanediamine or an N, N, N', N'-tetramethylhexane- And a method for removing carbon dioxide using the same.

Patent No. 2871334 specification Japanese Patent Publication No. 2009-529420 Japanese Patent Application Laid-Open No. 2010-110749 Japanese Patent Application Laid-Open No. 2010-188336 Japanese Patent Application Laid-Open No. 2010-201422 Japanese Patent Publication No. 2011-528993

As described above, in the separation and recovery of carbon dioxide, an absorption liquid of carbon dioxide having a low energy consumption and low corrosiveness is required.

Accordingly, it is an object of the present invention to provide an aqueous solution and a method capable of not only absorbing carbon dioxide in a gas with high efficiency, but also realizing high-efficiency removal of carbon dioxide and recovering high purity carbon dioxide with low energy consumption. More specifically, the present invention relates to an aqueous solution capable of absorbing and desorbing a large amount of carbon dioxide per unit amount of aqueous solution, having a low energy required for desorbing carbon dioxide, absorbing carbon dioxide efficiently and desorbing it to recover high purity carbon dioxide, And to provide a method of absorbing and recovering the same.

The present inventors have eagerly studied an absorbent that can efficiently absorb and desorb carbon dioxide to recover high purity carbon dioxide. As a result, the aqueous solution containing the amino alcohol compound represented by the formula (1) and the amine compound represented by the formula (2) has a high absorption and desorption amount of carbon dioxide and a good absorption rate, The recovery of carbon dioxide in one cycle is greatly improved, and as a result, the carbon dioxide can be recovered at a lower energy consumption amount, and the present invention has been accomplished.

That is, the present invention constitutes the following items 1 to 5.

Item 1. An aqueous solution for absorbing and recovering carbon dioxide from a gas containing carbon dioxide, the aqueous solution comprising an aminoalcohol compound represented by the formula (1) and an amine compound represented by the formula (2).

[Chemical Formula 1]

(Wherein R represents an alkyl group having 1 to 5 carbon atoms and n represents 1 or 2)

(2)

(Wherein X represents -NR 1 R 2, Y represents -NR 3 R 4, R 1, R 2, R 3 and R 4 are the same or different and each represents an alkyl group having 1 to 3 carbon atoms, and m represents an integer of 3 to 7)

Item 2. The composition according to item 1, wherein the total weight concentration of the amino alcohol compound and the amine compound is 20 to 80%, the weight concentration of the amino alcohol compound is 10 to 70%, and the weight concentration of the amine compound is 1 to 50% 1 >, wherein R < 1 >

Item 3. The aqueous solution according to Item 2, wherein the weight concentration of the amino alcohol compound is 30 to 60% and the weight concentration of the amine compound is 1 to 40%.

Item 4. The aqueous solution according to any one of Items 1 to 3, wherein R in the amino alcohol compound is an alkyl group having 2 to 4 carbon atoms and m in the amine compound is an integer of 5 to 7 .

Item 5. A process for producing an aqueous solution, comprising the steps of bringing the aqueous solution according to any one of Items (1) to (4) into contact with a gas containing carbon dioxide to absorb carbon dioxide from the gas and

(2) a step of heating the carbon dioxide-absorbed aqueous solution obtained in the above (1) to desorb and recover the carbon dioxide

/ RTI > and a method for absorbing and recovering carbon dioxide.

In the separation and recovery of carbon dioxide using the aqueous solution according to the present invention, the recovery of carbon dioxide per cycle is increased in the absorption and desorption of carbon dioxide, the separation and recovery energy of carbon dioxide per unit weight of the aqueous solution is lowered and the high- Can be recovered. Further, the reduction of the circulating flow rate in the absorption and desorption cycles leads to the miniaturization of the absorption tower, the desorption tower, and the apparatus attached thereto.

In general, widely used MEAs exhibit high corrosion resistance to carbon steels, and in particular, corrosion resistance increases at a high concentration. However, the corrosion resistance of the aqueous solution used in the present invention is low, and there is no need to use a high- .

Hereinafter, the present invention will be described in detail.

An aqueous solution for absorbing and recovering carbon dioxide

The aqueous solution for absorbing and recovering carbon dioxide from the gas containing carbon dioxide of the present invention is characterized by containing an aminoalcohol compound represented by the formula (1) and an amine compound represented by the formula (2).

[Chemical Formula 1]

(Wherein R represents an alkyl group having 1 to 5 carbon atoms and n represents 1 or 2)

(2)

(Wherein X represents -NR 1 R 2, Y represents -NR 3 R 4, R 1, R 2, R 3 and R 4 are the same or different and each represents an alkyl group having 1 to 3 carbon atoms, and m represents an integer of 3 to 7)

The alkyl group having 1 to 5 carbon atoms may be either linear or branched, and examples thereof include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec- Pentyl and the like. R is preferably an alkyl group having 2 to 4 carbon atoms, for example, ethyl, n-propyl, isopropyl, n-butyl and isobutyl, more preferably isopropyl, n-butyl and isobutyl.

The alkyl group having 1 to 3 carbon atoms may be either straight-chain or branched, and examples thereof include methyl, ethyl, n-propyl and isopropyl. R 1, R 2, R 3 and R 4 are preferably methyl and ethyl.

m is preferably from 5 to 7, and more preferably 5. [

Specific examples of the aminoalcohol compound represented by the general formula (1) include N-ethyl ethanolamine, N-propyl ethanolamine, N-isopropyl ethanolamine, N-butyl ethanolamine, N-isobutyl ethanolamine, 1-propanol, 3-n-butylamino-1-propanol, 3-isobutylamino-1-propanol and the like. These can be used industrially.

Specific examples of the amine compound represented by Formula 2 include N, N, N ', N'-tetramethyl-1,4-butanediamine, N, N, N' N, N ', N'-tetramethyl-1,6-hexanediamine, N, N, N' N, N ', N'-tetraethyl-1,4-butanediamine, N, N, N' , N, N, N ', N'-tetraethyl-1,8-octanediamine and the like, and these can be used industrially.

The concentration of the aqueous solution of the present invention is preferably such that the total weight concentration of the aminoalcohol compound represented by the formula (1) and the amine compound represented by the formula (2) is 20 to 80%, the weight concentration of the aminoalcohol compound represented by the formula To 70% by weight, the weight concentration of the amine compound represented by the general formula (2) is 1 to 50%, more preferably the weight concentration of the amino alcohol compound represented by the general formula (1) is 30 to 60% The weight concentration is 1 to 40%.

The aqueous solution of the present invention may contain, if necessary, stabilizers (antioxidants and the like) for securing the chemical or physical stability of the aqueous solution, inhibitors (corrosion inhibitors and the like) for preventing material deterioration of the apparatus or equipment using the aqueous solution of the present invention, May be added.

The aminoalcohol compound represented by the formula (1) and the amine compound represented by the formula (2) are commercially available or can be prepared by a known method.

Examples of the gas containing carbon dioxide include coal-fired power plants using coal, heavy oil, natural gas, etc., boilers at a manufacturing plant, kilns at cement plants, blast furnaces at steel mills for reducing iron oxides, The exhaust gas from a coal-gasification combined cycle power plant, natural gas, and a reformed gas can be used for steelmaking, and the concentration of carbon dioxide in the gas is usually about 5 to 30% by volume, 25 vol.%. In this range of the carbon dioxide concentration, the action and effect of the present invention can be suitably exercised. The gas containing carbon dioxide may contain gases such as water vapor, CO, H ₂ S, COS, SO ₂ , NO ₂ , and hydrogen in addition to carbon dioxide.

How to absorb and recover carbon dioxide

The carbon dioxide absorbing and recovering method of the present invention is characterized by comprising the following steps.

(1) a step of bringing the aqueous solution into contact with a gas containing carbon dioxide to absorb carbon dioxide from the gas,

(2) A step of heating the aqueous solution in which the carbon dioxide absorbed in (1) is absorbed to desorb and recover the carbon dioxide.

ㆍ Carbon dioxide absorption process

The method of the present invention includes a step of bringing the aqueous solution into contact with a gas containing carbon dioxide to absorb carbon dioxide from the gas, but there is no particular limitation on a method of contacting and absorbing a gas containing carbon dioxide into the aqueous solution of the present invention. For example, there are a method of bubbling a gas containing carbon dioxide into the aqueous solution to absorb the gas, a method of spraying the aqueous solution in a mist state (spraying or spraying method) in a gas stream containing carbon dioxide, And a method in which the aqueous solution is countercurrently contacted with a gas containing carbon dioxide in an absorption tower in which the aqueous solution is introduced.

The temperature at which the gas containing carbon dioxide is absorbed into the aqueous solution is usually from room temperature to 60 占 폚 or lower, preferably 50 占 폚 or lower, and more preferably from 20 占 폚 to 45 占 폚. The lower the temperature, the more the absorption amount increases. However, the temperature to which the temperature is lowered is determined by the gas temperature of the exhaust gas, the heat recovery target, and the like. The pressure at the time of carbon dioxide absorption is usually set at almost atmospheric pressure. In order to increase the absorption performance, it is possible to pressurize to a higher pressure, but it is preferable to perform under atmospheric pressure since the energy consumption required for compression is suppressed.

The gas containing carbon dioxide is the same as described above.

ㆍ Carbon dioxide Tally  fair

The method of the present invention includes a step of heating the aqueous solution obtained in the carbon dioxide absorption step to desorb and recover the carbon dioxide.

Examples of a method for removing carbon dioxide from an aqueous solution that has absorbed carbon dioxide and recovering pure or highly concentrated carbon dioxide include a method in which an aqueous solution is heated and removed by bubbling in a kiln like a distillation, And a method in which the liquid interface is expanded and heated in a desorption column containing a filler. As a result, carbon dioxide is liberated from the bicarbonate ions.

The liquid temperature at the time of carbon dioxide desorption is usually 70 ° C or higher, preferably 80 ° C or higher, and more preferably 90 to 120 ° C or so. The higher the temperature, the more the absorption is increased. However, since the energy required for heating the absorption liquid increases when the temperature is raised, the temperature is determined according to the gas temperature in the process, the heat recovery target, and the like. The amine aqueous solution after the carbon dioxide is desorbed is sent again to the carbon dioxide absorption step to be circulated (recycled). During this process, the heat applied in the carbon dioxide desorption process can be effectively used for raising the temperature of the aqueous solution by heat exchange with an aqueous solution for the carbon dioxide desorption process from now on in the circulation process, thereby reducing the energy of the whole process.

The purity of the carbon dioxide recovered in this way is usually 99% by volume or more, which is very high in purity and can be used in the chemical industry or the food industry. The recovered carbon dioxide can also be provided for underground isolation in Enhanced Oil Recovery (EOR) or CCS, which is currently under practical use.

<Examples>

Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

1st Example

50% by weight of 2- (isopropylamino) ethanol (IPAE, manufactured by Tokyo Kasei Kogyo K.K.), and 50% by weight of N, N, N 10% by weight of N, N'-tetramethyl-1,6-hexanediamine (TMHA, manufactured by Tokyo Kasei Kogyo Co., Ltd.). A mixed gas containing 20% by volume of carbon dioxide and 80% by volume of nitrogen at a rate of 0.7 liter / min under atmospheric pressure was passed through a glass filter having an eye roughness of 100 탆 and a diameter of 13 mm to form bubbles Minute.

The carbon dioxide concentration in the gas at the inlet of the absorption inlet and the outlet of the absorption liquid was continuously measured by an infrared type carbon dioxide system (HORIBA GAS ANALYZER VA-3000) and the amount of carbon dioxide absorption was measured from the difference of the carbon dioxide flow rate at the inlet and the outlet. If necessary, the amount of inorganic carbon in the absorption liquid was measured by a gas chromatography-based total organic carbon system (SHIMADZU TOC-VCSH) and compared with a value calculated from an infrared carbon dioxide system. The saturated water absorption amount was set at a point when the carbon dioxide concentration at the outlet of the absorption liquid coincided with the carbon dioxide concentration at the inlet. The absorption rate varies depending on the absorption amount, but is measured based on the absorption rate at the time of absorbing one-half of the saturated absorption amount. Subsequently, in the same gas stream, the liquid temperature was raised to 70 DEG C in water, and the amount of carbon dioxide desorption was measured under the same conditions for 60 minutes.

The calorific value was measured by a differential thermal calorimeter (SETARAM, DRC Evolution) by means of two identical absorption devices with a stirrer to blow a predetermined amount of carbon dioxide into only one of the reactors at 40 ° C, Respectively.

Second to fifth Example

Except that an aqueous solution containing IPAE and TMHA at the concentrations shown in Table 1 was used instead of the aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA, the saturation absorption amount and absorption rate of carbon dioxide , Calorific value and desorption amount were measured.

6th Example

Except that an aqueous solution containing 3-isopropylamino-1-propanol (IPAP) and TMHA at the concentrations shown in Table 1 was used in place of the aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA, The saturation absorption amount, the absorption rate, the calorific value and the desorption amount of carbon dioxide were measured.

Seventh to Ninth Example

Except that an aqueous solution containing IPAP and TMHA in the concentration shown in Table 1 was used instead of the aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA, the saturation absorption amount and absorption rate of carbon dioxide And the amount of desorption was measured.

10th to 12th Example

Except that an aqueous solution containing 2-ethylamino-1-ethanol (EAE) and TMHA in the concentrations shown in Table 1 was used in place of the aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA. In the same manner, the saturation absorption amount, absorption rate and desorption amount of carbon dioxide were measured.

EAE is easier and more economical to procure than IPAE, so EAE is advantageous from the point of view of the cost of the absorption liquid. As is clear from the comparison of the eighth to ninth comparative examples, even when EAE is selected, the amount of carbon dioxide desorbed, which is very important as the performance of the absorption liquid, is significantly improved by adding the amine compound of the present invention.

13th to 15th Example

Except that an aqueous solution containing IPAE and N, N, N ', N'-tetramethyl-1, 4-butanediamine (TMBA, manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used in place of the aqueous solution containing IPAE and TMHA. The saturation absorption amount and the desorption amount of carbon dioxide were measured in the same manner as in the examples. As a result, the saturated water uptake and desorption amount per unit absorption amount of carbon dioxide was improved as compared with the case of using an IPAE-only aqueous solution.

First to third Comparative Example

Except that an aqueous solution containing only IPAE 30, 55 and 60 wt% was used instead of the aqueous solution containing 50 wt% IPAE and 10 wt% TMHA, the saturation absorption amount, absorption rate and calorific value And the amount of desorption was measured.

Fourth Comparative Example

Except that an aqueous solution containing 52% by weight of IPAE and 3% by weight of piperazine (PZ) was used instead of the aqueous solution containing 50% by weight of IPAE and 10% by weight of TMHA, Absorption amount, absorption rate, calorific value and desorption amount were measured.

Fifth to sixth Comparative Example

Except that an aqueous solution containing 30 wt% or 50 wt% of TMHA was used in place of the aqueous solution containing 50 wt% of IPAE and 10 wt% of TMHA, the saturation absorption amount, absorption rate and calorific value And the amount of desorption was measured.

Seventh Comparative Example

The saturation absorption amount and desorption amount of carbon dioxide were measured in the same manner as in Example 1 except that an aqueous solution containing 30 wt% of IPAP was used instead of the aqueous solution containing 50 wt% of IPAP and 10 wt% of TMHA.

8th to 9th Comparative Example

A saturated absorption amount and a desorption amount of carbon dioxide were measured in the same manner as in Example 1 except that an aqueous solution containing 30% by weight or 54% by weight of EAE was used instead of the aqueous solution containing 50% by weight of EAE and 10% .

Table 1 shows the results obtained in the first to fifteenth embodiments and the first to ninth comparative examples. In the table,% represents weight%.

(Embodiment 1)

The carbon dioxide saturation absorption at 40 DEG C was 156 g per kg of aqueous solution. The carbon dioxide desorption at 70 캜 was 91 g per kg absorbed. The purity of recovered carbon dioxide was 99.8%. From this result, the saturated absorption amount and the desorption amount per unit absorption liquid were very large as compared with the first comparative example, and the performance of the absorption liquid of the present invention was confirmed.

(Comparative Examples 1 to 3)

At a low concentration of 30% by weight, the absorption rate is fast, but at 60% by weight, a remarkable decrease in the absorption rate is observed. As a result, the saturation absorption amount and the desorption amount in all cases are lower than those of the first to fifth embodiments Respectively.

(Comparative Example 4)

Piperazine is known as a reaction activator in the absorption of carbon dioxide in an aqueous solution of alkanolamines and has an effect of improving the saturation absorption amount and absorption rate. From the results of Table 1, it can be seen that the first to fifth embodiments are advantageous in terms of the amount of desorption.

(Comparative Examples 5 to 6)

In the case of the aqueous solution containing only TMHA, a sufficient effect was not obtained in terms of the desorption amount at 30 wt%, and the absorption rate was extremely lowered at 50 wt%. From the results shown in Table 1, it can be seen that the embodiment is more advantageous.

(Comparative Example 7)

The amount of desorption showed a lower value compared with the sixth to ninth embodiments.

(Comparative Examples 8 to 9)

In all cases, the amount of desorption showed a lower value compared to the tenth to twelfth examples.

1st Test Example

The aqueous solution of the first embodiment was subjected to a corrosion test on an SS400 metal test cylinder. The test was carried out under the condition of 130 占 폚 for 48 hours under a saturated atmosphere of carbon dioxide using Hastelloy's autoclave. As a result, the corrosion to the SS400 for the aqueous solution of the first embodiment was frontal corrosion and the corrosion rate was calculated to be 0.13 mm / year. From this result, it was judged to have some corrosiveness.

Claims (5)

An aqueous solution for absorbing and recovering carbon dioxide from a gas containing carbon dioxide, the aqueous solution comprising an aminoalcohol compound represented by formula (1) and an amine compound represented by formula (2).
[Chemical Formula 1]

(Wherein R represents an alkyl group having 1 to 5 carbon atoms and n represents 1 or 2)
(2)

(Wherein X represents -NR 1 R 2, Y represents -NR 3 R 4, R 1, R 2, R 3 and R 4 are the same or different and each represents an alkyl group having 1 to 3 carbon atoms, and m represents an integer of 3 to 7) The method according to claim 1,
Wherein the total weight concentration of the amino alcohol compound and the amine compound is 20 to 80%, the weight concentration of the amino alcohol compound is 10 to 70%, and the weight concentration of the amine compound is 1 to 50% , Aqueous solution. 3. The method of claim 2,
Wherein the weight concentration of the amino alcohol compound is 30 to 60% and the weight concentration of the amine compound is 1 to 40%. The method according to claim 1,
Wherein R in the aminoalcohol compound is an alkyl group having 2 to 4 carbon atoms and m in the amine compound is an integer of 5 to 7. (1) a step of contacting the aqueous solution according to claim 1 with a gas containing carbon dioxide to absorb carbon dioxide from the gas, and
(2) a step of heating the carbon dioxide-absorbed aqueous solution obtained in the above (1) to desorb and recover the carbon dioxide
/ RTI &gt; The method of claim 1,